After Facebook's purchase of photo-sharing site Instagram for $1billion, various firms have sized up photo-board network Pinterest as ripe for purchase.

Business magazine Forbes said the network could have a value of up to $7.7 billion - and others have made more modest estimates around the $1 billion mark.

But as investors circle, the most important observers of all seem to be losing interest - user numbers have slumped in the past month.

Numbers for the photo-sharing site have slumped in the past month after a meteoric rise throughout last year and into early 2012

Pinterest's numbers have slumped in the past month: t is speculated that the people who signed up to the site simply to try out the latest fad have now decided that it is not for them

Dying craze: New figures reveal that the number of people joining Pinterest through Facebook have seriously declined this month

The majority of Pinterest users
sign up through Facebook and the number of people doing this has
significantly dropped in the past few months, according to data
collected by the Business Insider.

The site works as a 'timeline app'
within Facebook, allowing Facebook users to use one log-in across both
and share 'pins' - Pinterest's term for posts - via a Facebook page.

AppData,
which monitors how often users of third-party apps and other web sites
interact with Facebook, has shown the site's decline.

The
site’s growth slowed last month and it is now revealed that users are
turning away from the network, which was launched in March 2010.

Monthly active users are down from 11.15 million on April 1 to 8.3 million today.

Rapid growth: Since its launch in March 2010 the site quickly grew in popularity, as this graph shows, but now new figures reveal Pinterest is losing users this month

With endorsements from President Barack
Obama and Mark Zuckerburg the picture-sharing program that allows users to essentially create 'vision boards' of their favorite things, was quickly labelled the
social media craze of 2012.

It
is speculated that the people who signed up to the site simply to try
out the latest fad have now decided that it is not for them.

The
12-million-strong social site works with a Facebook login, and allows
users to create 'boards' of 'pins' - pictures and links from the
internet.

The site, which is still invitation-only, has hit 12 million unique visitors in the U.S - the fastest social network ever to hit the figure.

Mashable
says, 'While it’s too early to say Pinterest poses a threat to Facebook
in any way, the simple content sharing site can easily be called the
hottest startup of 2012.'

Pinterest says it 'does not currently disclose figures', but analyst
estimates have said that much of its traffic is driven by female
interest.

December
data for Experian Hitwise put the figure at 58 per cent female, driven
by the photo-sharing site's focus on arts and crafts.

The site is built around visual 'Pinboards' where users share pictures and links they have found online. You find people to follow by 'telling' the site your interests

Pinterest launched in March 2010.

It's
been described as a visual version of Twitter. Like Twitter, you can
'follow' users who share your interests, and quick, brief picture posts
make up the bulk of posts on the site.

Unlike Facebook and Twitter, posts appear as a 'pinboard' of images built according to user interests.

Smart
Company says, 'You create a pin board and share it with others to view,
add and comment. Capturing the imagination of users seems to be
Pinterest's application of visuals to communicate; whereas Facebook and
Google+ rely on text-based updates and sharing, Pinterest is like
swapping football cards or holiday pictures.'

Happpier times? Experian's chart of Pinterest's users rising throughout 2011, going from around 50,000 in March to 11 million in December

The
site works as a 'timeline app' within Facebook, allowing Facebook users
to use one log-in across both and share 'pins' - Pinterest's term for
posts - via a Facebook page.

'Lots
of people use Pinterest to get inspiration for the most important
projects in their life. People use Pinterest to plan their vacations,
redecorate their homes, and create menus for holiday dinners,' says the
site.

'You can now share
all of these pins on your Facebook Timeline and look back at all of your
projects and inspirations across the year! To add pins to your Facebook
Timeline, click the button on the top of your screen.'